Long story short: Drilling carbon steel (i.e. not stainless steel) two most expensive bits in an expensive drill bit set chip on first of four holes.

Long story long: I've been planning to bolt a safe down to the concrete foundation for a while. Part of the hesitancy was this safe wasn't predrilled so I had to drill steel first, then through that hole drill concrete, and then install the anchor bolt system.

I like to research and stew on things, and I eventually decided that I was going to purchase 14-piece M42 Cobalt (8% cobalt vs the less expensive 5% cobalt M35) "jobber" drill bit set which was the most expensive option I was considering. I only have to make 4 holes, and decided I was going to make each hole in 3 steps (3/32", 3/16", and 3/8"). I made 2 holes with 3/32" and 3/16" (went well) then swapped out the battery and proceeded to drill the 3/8" hole. I used 3 in 1 oil to lubricate the bit & hole, and stopped frequently to relube. 3/8" bit chips first hole, but it finished that hole and well as the other one (slower though).

I grabbed my concrete bit and realized my 2nd problem (3/8" concrete bit doesn't fit through 3/8" hole) and since the set doesn't include I 7/16" I grabbed the 1/2" bit. Same routine with lubrication. On the first hole, the 1/2" bit chips even larger than the 3/8" bit but it still slowly finishes the 2nd hole.

For the 3rd and 4th holes, I used the 1/8", 1/4" and 1/2" bits. Same lubrication regimen as before and the 1/8" and 1/4" bits were flawless. The 1/2" bit proceeded to get slower every hole, but at the end of the day it worked and I now have 4 bolts anchoring my safe to the foundation.

Question:
What would you do about the two most expensive drill bits (replacing these 2 bits would be 90% the cost of the 14-piece set) in the set being chipped after first hole?

Choices:
Suck it up.
Contact the manufacturer as it's a warranty problem
Send it back to Amazon as that is what the 30-day return policy is for

 

IMO, you need an option for "Learn how to grind'em."

Once you're able to grind your own drills a choir of angels will bathe you in satisfaction.

Get a drill point gage (about $5 for a cheapie) & learn to put the point back to cutting geometry.

M42 is Cobalt High Speed Steel and is good stuff. I probably wouldn't have stepped the hole sizes. You likely got a big grabbing bite which cheesed off your corners. Going right to the size you needed was a better option, IMO. Pilot holes can be a blessing or a curse. Sorry you experienced the latter.

Would a Drill Doctor be useful? Sharpen the bits and carry on?

We finally bought one at work... love it.

quote:

Originally posted by vthoky:
Would a Drill Doctor be useful? Sharpen the bits and carry on?

This ^^^^^. I have owned one for years, and it has paid for itself many times over......plus I have sharp bits!!!

quote:

Originally posted by vinnybass:
IMO, you need an option for "Learn how to grind'em."

Appreciate the alternative option, but as far as the poll it fits under my "suck it up" option

quote:

Originally posted by vthoky:
Would a Drill Doctor be useful? Sharpen the bits and carry on?

Thanks for the alternative option, but as far as the poll it fits under my "suck it up" option

If you weren't using the bits in an abusive manner or in a manner they were not intended, it's a manufacturer issue.

Hate to say it, TT, but you should suck it up. It was end-user error.

First of all those Bosch twist drill bits may be better than consumer/homeowner average, but they probably won't hold a candle to the Real Deal, such as Walter, Norseman, or Champion.

Secondly: Drilling holes like that in hard steel with a hand drill is tricky. Yes, it can be done, but it has to be done properly (see below) and you're supposed to use jobber drill bits. That's what they're made for.

In giving the less-expensive jobber drill bit set a pass you actually did the wrong thing. They have less cobalt to make them less brittle, because it's far harder not to do with a hand drill things that make twist drill bits chip than it is with a drill press. (My good DP twist drill bit set will never be chucked into a hand drill.)

Finally: You used the bits incorrectly. When drilling multiple passes in hard steel with twist bits, no hole should be (much) larger than the point of the succeeding drill bit, otherwise the cutting edge will dig in too far, too fast and seize, chip, or both.

You need to make smaller increments between the larger sizes more than the smaller ones.
That doesn't get the drills sharpened but will help in the future.

Buy yourself two or three Unibits of different sizes and from then on use drill bits to start holes in steel and the Unibits to ream them out to the proper diameter. They will outlast you.

quote:

Originally posted by ensigmatic:
Hate to say it, TT, but you should suck it up. It was end-user error.

First of all those Bosch twist drill bits may be better than consumer/homeowner average, but they probably won't hold a candle to the Real Deal, such as Walter, Norseman, or Champion.

Secondly: Drilling holes like that in hard steel with a hand drill is tricky. Yes, it can be done, but it has to be done properly (see below) and you're supposed to use jobber drill bits. That's what they're made for.

In giving the less-expensive jobber drill bit set a pass you actually did the wrong thing. They have less cobalt to make them less brittle, because it's far harder not to do with a hand drill things that make twist drill bits chip than it is with a drill press. (My good DP twist drill bit set will never be chucked into a hand drill.)

Finally: You used the bits incorrectly. When drilling multiple passes in hard steel with twist bits, no hole should be (much) larger than the point of the succeeding drill bit, otherwise the cutting edge will dig in too far, too fast and seize, chip, or both.

Ding ding ding. The bits were abused. Also, next time use an oil that’s actually designed for drilling/cutting like Tap Magic. It makes a HUGE difference.

I'm sure this is just run of the mill mild steel and likely very thin. I'm not sure if the bottom of the safe is double walled. If not, I think a skinny step (unibit) would be best as mentioned above.

Drilling thin metals with a twist bit is rarely the best option due to the chipping issue. It has been for me at least.

I'm not a machinist. You don't say what brand or quality safe you are working on. I would doubt that the floor of the average $1000 safe is hardened steel. Also the viscosity of 3 in 1 oil is pretty thin. I would have used something thicker and less watery like SAE 30. I have drilled the bottom of several safes with inexpensive bits and never chipped one.

quote:

Originally posted by shiftyvtec:
I'm sure this is just run of the mill mild steel and likely very thin. I'm not sure if the bottom of the safe is double walled.

7 gauge (3/16") steel. Not double walled.

Did you have the floor of the safe elevated while you drilled or was it sitting on the floor?

I use cheap bits to run through all manner of lighter safes, and can even usually do holes up to 1/2" without any predrilling, lubrication, or other issues.

3/16" is thicker than I expected.

quote:

Originally posted by a1abdj:
Did you have the floor of the safe elevated while you drilled or was it sitting on the floor?

Yes and it was higher than drill bit length so physically impossible for bit to hit something after boring through

quote:

Originally posted by a1abdj:
I use cheap bits to run through all manner of lighter safes, and can even usually do holes up to 1/2" without any predrilling, lubrication, or other issues.

Interesting. Would 7 gauge be a single 1/2 hole or a series of progressively larger holes? For thicker safes, do you switch to more expensive bits?

In the late 1990s I bought two 24" x 24" x ½" steel plates. When the shop asked me how thick I wanted, I originally guessed, "About two inches". So I telegraphed right off the bat I had no idea what I was talking about. They explained the ½" stock was 22# per sq.ft. OK, I went with ½". Then the holes. I thought I'd save $5 per hole and drill them myself.

The guy was cool and let me know it would be far easier to let the shop do it. "You have to put some weight behind the bit", he said. I'm guessing he was talking about several hundred pounds. Kept perfectly plumb to the cut.

So as a guy who has shaped metal for years at that point, I still had no idea what I was talking about.

User error, probably. Send them back? Your call, but Bezos is not out-of-pocket.

Suck it up. Not that you had much of a choice at that point, but going 3/8 to 1/2 was asking for trouble. Plus, 3/8 is a big hole, so where does most of your 3 in 1 oil wind up? For a 1/2 hole I'd start with a 3/16 bit, drill about half way, then switch to tbe 1/2. I like having a pool of oil in the hole as it's being drilled. Like others have said, thicker oil.

Drill bits are like pencils... They get dull, need re-sharpening, and eventually get thrown away. High Speed steel drill bits work great and are less prone to chipping.

First off, a $30 set of drill bits are not exactly high quality. You can get a very good quality set IF you know which ones are good.....ie Makita, Dewalt, Milwaukee's $30 sets are pretty good.

That being said, he shouldn't have chipped the drill bits going from 3/16 to 3/8" drill bits. I'd send them back. I've drilled all kinds of metal and put drill bits through all kinds of abuse, no oil, etc. and have never chipped any except once. I have dulled drill bits yes, but had pieces fly off the first time or 15th time I used them, no. It's poor metallurgy.